The present invention relates to a new and improved way of attaching a welded wire soil-reinforcing grid to a facing system for use in mechanically stabilized earth (MSE) retaining structures. The invention is an improvement over the prior art in that it places even stress on the tension elements, defined herein as the longitudinal wires of the soil-reinforcing grid. Further, the present invention allows a welded wire grid to translate in a horizontal plane with respect to the facing panel.
One form of art relies on attaching welded wire reinforcing grid by forming a loop or special crimp in individual longitudinal wires of the grid. The loops are formed by bending the wire 180xc2x0 and welding the bent end to the longitudinal wire. This forms an integrated loop. This apparatus appears in U.S Pat. No. 4,725,170-Davis. The loop of the welded wire grid is then placed through a coiled anchor that is cast into the back of a concrete face panel. The loop of the soil reinforcing grid and anchor are in a vertical plane which is perpendicular to the back face of the panel.
In another prior art MSE system the longitudinal wire is bent 900 and attached with a plate and bolt to the back of the facing unit. In another system the longitudinal wire is crimped and joined to an anchor with a connection pin. These can be seen in U.S. Pat. Nos. 5,749,680xe2x80x94Hilfiker and 4,324,508xe2x80x94Hilfiker, respectively. The arrangement of U.S. Pat. No. 5,749,680 allows the reinforcing grids to translate in a horizontal plane with respect to the facing panels.
Other prior art places the transverse wire of the welded wire grid work behind a loop that is formed in a panel anchor. The welded wire grid is attached to the panel anchor with a connection pin. This appears in U.S. Pat. No. 5,259,704-Orgorchock.
Still other prior art bends a single longitudinal wire 180xc2x0 to form a wire hairpin configuration. Welded to the paired longitudinal wires are transverse wires, which form a welded wire grid work. This combination forms an integral loop at the lead end of the soil-reinforcing element. The anchoring element protruding from the back of a panel is a formed loop. The soil-reinforcing element and loop are joined with the aid of a snap together mechanism. This can be seen in the prior art Alviterra connection shown in FIG. 1.
One block system utilizes a reinforcing element having parallel longitudinal wires with loops formed in each end. Each longitudinal wire is placed in counter bores formed in the top surface of a block. Rods are inserted through the counter bores and loops to secure the reinforcing element in the block. This arrangement, can be found in U.S. Pat. No. 5,487,623-Anderson.
A second block system utilizes a flat polymeric soil-reinforcing mat that is placed between blocks. The soil-reinforcing mat is sandwiched between the blocks. The blocks are secured together by a pin that anchors the grid. This can be seen in U.S. Pat. No. 4,914,876-Forsberg.
In U.S. Pat. No. 5,807,030-Anderson, a welded wire grid is formed with loops in each end the loops are then deflected toward one another so each loop through bore-lines up. The welded wire grid is then attached to a panel or block by passing a pin or bolt through the through-bore.
U.S. Pat. No. 6,050,748-Anderson discloses a welded wire grid in which a pair of substantially straight parallel wires are welded to a flat plate that has at least one through bore in the end nearest the MSE structure (see FIG. 55). The flat plate is then attached to the panel or block with the aid of a pin. This patent is also of interest in that FIGS. 47 to 52 disclose a connection which includes overlapping loops which are engaged between or over connecting elements embedded in the face panels.
A principal object of the present invention is to provide an apparatus and method for attaching the face of an earthen retaining structure to a soil-reinforcing element through means of a pin element attached to the reinforcing element. Attachment is achieved by extending the pin element through a connection element on the face, or into a concrete block connection element for the blocks making up the face. The pin element is attached directly to longitudinal wires of the reinforcing element and the pin is attached to a face so it is free to rotate about the connection axis. This allows the soil-reinforcing element to be skewed at an angle to the face. The connection is mechanical and does not rely on the weld shear of a transverse wire of the grid work. Further, the soil-reinforcing element can be rotated to pass obstructions. Additionally, since two longitudinal wires are utilized in lieu of one there is twice the strength available.